Liquid crystal composition and liquid crystal display device

ABSTRACT

The invention is to provide a liquid crystal composition that satisfies at least one of characteristics such as a high maximum temperature of a nematic phase, a low minimum temperature of a nematic phase, a small viscosity, a suitable optical anisotropy, a large negative dielectric anisotropy, a large specific resistance, a high stability to ultraviolet light and a high stability to heat, or that is suitably balanced regarding at least two of the characteristics; and is to provide a AM device that has a short response time, a large voltage holding ratio, a large contrast ratio, a long service life and so forth, wherein the liquid crystal composition has negative dielectric anisotropy and includes a two-ring compound having a large negative dielectric anisotropy and having at least three fluorines at the lateral positions as a first component, a specific two-ring or three-ring compound having a pyran ring as a second component, a specific compound having a small viscosity as a third component and a specific compound having a large negative dielectric anisotropy as a fourth component, and the liquid crystal display device contains this composition.

FIELD OF THE INVENTION

The invention relates mainly to a liquid crystal composition suitablefor use in an active matrix (AM) device and so forth, and an AM deviceand so forth that contains the composition. More specifically, theinvention relates to a liquid crystal composition having negativedielectric anisotropy, and a device containing the composition andhaving a mode such as in-plane switching (IPS), vertical alignment (VA)or polymer sustained alignment (PSA).

BACKGROUND OF THE INVENTION

In a liquid crystal display device, a classification based on anoperating mode for liquid crystals includes modes of phase change (PC),twisted nematic (TN), super twisted nematic (STN), electricallycontrolled birefringence (ECB), optically compensated bend (OCB),in-plane switching (IPS), vertical alignment (VA) and polymer sustainedalignment (PSA). A classification based on a driving mode in the deviceincludes a passive matrix (PM) and an active matrix (AM). The PM isfurther classified into static, multiplex and so forth, and the AM isclassified into a thin film transistor (TFT), a metal-insulator-metal(MIM) and so forth. The TFT is further classified into amorphous siliconand polycrystal silicon. The latter is classified into a hightemperature type and a low temperature type according to the productionprocess. A classification based on a light source includes a reflectiontype utilizing natural light, a transmission type utilizing a backlightand a semi-transmission type utilizing both natural light and abacklight.

These devices contain a liquid crystal composition having suitablecharacteristics. The liquid crystal composition has a nematic phase.General characteristics of the composition should be improved to give anAM device having good general characteristics. Table 1 below summarizesthe relationship between the general characteristics of the two. Thegeneral characteristics of the composition will be explained furtherbased on a commercially available AM device. The temperature range of anematic phase relates to the temperature range in which the device canbe used. A desirable maximum temperature of the nematic phase is 70° C.or higher and a desirable minimum temperature of the nematic phase is−10° C. or lower. The viscosity of the composition relates to theresponse time of the device. A short response time is desirable fordisplaying moving images on the device. Accordingly, a small viscosityof the composition is desirable. A small viscosity at a low temperatureis more desirable.

TABLE 1 General Characteristics of Composition and AM Device No. GeneralCharacteristics of Composition General Characteristics of AM Device 1wide temperature range of a nematic phase wide usable temperature range2 small viscosity ¹⁾ short response time 3 suitable optical anisotropylarge contrast ratio 4 large positive or negative dielectric lowthreshold voltage and small electric anisotropy power consumption largecontrast ratio 5 large specific resistance large voltage holding ratioand large contrast ratio 6 high stability to ultraviolet light and heatlong service life ¹⁾ A liquid crystal composition can be injected into aliquid crystal cell in a shorter period of time.

The optical anisotropy of the composition relates to the contrast ratioof the device. The product (Anxd) of the optical anisotropy (An) of thecomposition and the cell gap (d) of the device is designed so as tomaximize the contrast ratio. A suitable value of the product depends onthe kind of operating mode. In a device having a VA mode, a suitablevalue is in the range of 0.30 μm to 0.40 μm, and in a device having anIPS mode, a suitable value is in the range of 0.20 μm to 0.30 μm. Inthis case, a composition having a large optical anisotropy is desirablefor a device having a small cell gap. A large absolute value of thedielectric anisotropy in the composition contributes to a low thresholdvoltage, small electric power consumption and a high contrast ratio ofthe device. Accordingly, a large absolute value of the dielectricanisotropy is desirable. A large specific resistance of the compositioncontributes to a large voltage holding ratio and a large contrast ratioof the device. Accordingly, a composition having a large specificresistance is desirable at room temperature and also at a hightemperature in the initial stage. A composition having a large specificresistance is desirable at room temperature and also at a hightemperature after it has been used for a long time. The stability of thecomposition to ultraviolet light and heat relates to the service life ofthe liquid crystal display device. In the case where the stability ishigh, the device has a long service life. Such characteristics aredesirable for an AM device used in a liquid crystal projector, a liquidcrystal television and so forth.

A composition having positive dielectric anisotropy is used for an AMdevice having a TN mode. On the other hand, a composition havingnegative dielectric anisotropy is used for an AM device having a VAmode. A composition having positive or negative dielectric anisotropy isused for an AM device having an IPS mode. A composition having positiveor negative dielectric anisotropy is used for an AM device having a PSAmode. Examples of the liquid crystal composition having negativedielectric anisotropy are disclosed in the following patent documentsNo. 1 to No. 4.

PRIOR ART Patent Document

-   Patent document No. 1: JP 2001-316669 A.-   Patent document No. 2: US 2005/0104039 A.-   Patent document No. 3: JP 2001-262145 A.-   Patent document No. 4: JP 2001-115161 A.

A desirable AM device has characteristics such as a wide temperaturerange in which the device can be used, a short response time, a largecontrast ratio, a low threshold voltage, a large voltage holding ratioand a long service life. Response time that is even one millisecondshorter than that of the other devices is desirable. Thus, desirablecharacteristics of the composition include a high maximum temperature ofa nematic phase, a low minimum temperature of a nematic phase, a smallviscosity, a suitable optical anisotropy, a large positive or negativedielectric anisotropy, a large specific resistance, a high stability toultraviolet light and a high stability to heat.

OUTLINE OF THE INVENTION Subject to be Solved by the Invention

One of the aims of the invention is to provide a liquid crystalcomposition that satisfies at least one of characteristics such as ahigh maximum temperature of a nematic phase, a low minimum temperatureof a nematic phase, a small viscosity, a suitable optical anisotropy, alarge negative dielectric anisotropy, a large specific resistance, ahigh stability to ultraviolet light and a high stability to heat.Another aim is to provide a liquid crystal composition that is suitablybalanced regarding at least two of the characteristics. A further aim isto provide a liquid crystal display device that contains such acomposition. An additional aim is to provide a liquid crystalcomposition that has a suitable optical anisotropy which means a largeoptical anisotropy or a small optical anisotropy, a large negativedielectric anisotropy, a high stability to ultraviolet light and soforth, and is to provide an AM device that has a short response time, alarge voltage holding ratio, a large contrast ratio, a long service lifeand so forth.

Means for Solving the Subject

The invention concerns a liquid crystal composition that has negativedielectric anisotropy and includes at least one compound selected fromthe group of compounds represented by formula (1) as a first componentand at least one compound selected from the group of compoundsrepresented by formula (2) as a second component, and concerns a liquidcrystal display device containing this composition:

wherein R¹ and R² are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkenyloxyhaving 2 to 11 carbons, or alkenyl having 2 to 12 carbons in whicharbitrary hydrogen is replaced by fluorine; R³ and R⁴ are independentlyalkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenylhaving 2 to 12 carbons, or alkenyl having 2 to 12 carbons in whicharbitrary hydrogen is replaced by fluorine; the ring A is independently

and at least one of the rings A is

X¹, X², X³ and X⁴ are independently hydrogen, fluorine or chlorine, andat least three of X¹, X², X³ and X⁴ are fluorine; Z¹ is independently asingle bond, ethylene, methyleneoxy or carbonyl; and k is 1, 2 or 3.

Effect of the Invention

An advantage of the invention is a liquid crystal composition thatsatisfies at least one of characteristics such as a high maximumtemperature of a nematic phase, a low minimum temperature of a nematicphase, a small viscosity, a suitable optical anisotropy, a largenegative dielectric anisotropy, a large specific resistance, a highstability to ultraviolet light and a high stability to heat. One aspectof the invention is a liquid crystal composition that is suitablybalanced regarding at least two of the characteristics. Another aspectis a liquid crystal display device that contains such a composition. Afurther aspect is a composition that has a suitable optical anisotropy,a large negative dielectric anisotropy, a high stability to ultravioletlight and so forth, and an AM device that has a short response time, alarge voltage holding ratio, a large contrast ratio, a long service lifeand so forth.

Embodiment to Carry out the Invention

Usage of the terms in the specification and claims is as follows. Theliquid crystal composition of the invention and the liquid crystaldisplay device of the invention may be abbreviated to “the composition”and “the device,” respectively. “A liquid crystal display device” is ageneric term for a liquid crystal display panel and a liquid crystaldisplay module. “A liquid crystal compound” is a generic term for acompound having a liquid crystal phase such as a nematic phase or aseptic phase, and also for a compound having no liquid crystal phasesbut being useful as a component of a composition. Such a useful compoundhas a six-membered ring such as 1,4-cyclohexylene and 1,4-phenylene, anda rod-like molecular structure. An optically active compound and apolymerizable compound may occasionally be added to the composition.Even in the case where these compounds are liquid crystalline, thecompounds are classified as an additive herein. At least one compoundselected from the group of compounds represented by formula (1) may beabbreviated to “the compound (1).” “The compound (1)” means onecompound, or two or more compounds represented by formula (1). The samerules apply to compounds represented by the other formulas. “Arbitrary”is used not only in cases where the position is arbitrary but also incases where the number is arbitrary. However, it is not used in caseswhere the number is 0 (zero).

A higher limit of the temperature range of a nematic phase may beabbreviated to “the maximum temperature.” A lower limit of thetemperature range of a nematic phase may be abbreviated to “the minimumtemperature.” That “specific resistance is large” means that acomposition has a large specific resistance at room temperature and alsoat a high temperature in the initial stage, and that the composition hasa large specific resistance at room temperature and also at a hightemperature even after it has been used for a long time. That “a voltageholding ratio is large” means that a device has a large voltage holdingratio at room temperature and also at a high temperature in the initialstage, and that the device has a large voltage holding ratio at roomtemperature and also at a high temperature even after it has been usedfor a long time. When characteristics such as optical anisotropy areexplained, values which are obtained according to the measuring methodsdescribed in Examples will be used. A first component means onecompound, or two or more compounds. “The ratio of the first component”is expressed as a percentage by weight (% by weight) of the firstcomponent based on the total weight of the liquid crystal composition.The same rule applies to the ratio of a second component and so forth.The ratio of an additive mixed with the composition is expressed as apercentage by weight (% by weight) or weight parts per million (ppm)based on the total weight of the liquid crystal composition.

The symbol R¹ is used for a plurality of compounds in the chemicalformulas of component compounds. The meanings of R¹ may be the same ordifferent in two arbitrary compounds among these. In one case, forexample, R¹ of the compound (1) is ethyl and R¹ of the compound (1-1) isethyl. In another case, R¹ of the compound (1) is ethyl and R¹ of thecompound (1-1) is propyl. The same rule applies to the symbols R², R³and so forth.

The invention includes the following items.

-   Item 1. A liquid crystal composition that has negative dielectric    anisotropy and includes at least one compound selected from the    group of compounds represented by formula (1) as a first component    and at least one compound selected from the group of compounds    represented by formula (2) as a second component:

wherein R¹ and R² are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkenyloxyhaving 2 to 11 carbons, or alkenyl having 2 to 12 carbons in whicharbitrary hydrogen is replaced by fluorine; R³ and R⁴ are independentlyalkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenylhaving 2 to 12 carbons, or alkenyl having 2 to 12 carbons in whicharbitrary hydrogen is replaced by fluorine; the ring A is independently

and at least one of the rings A is

X¹, X², X³ and X⁴ are independently hydrogen, fluorine or chlorine, andat least three of X¹ , X², X³ and X⁴ are fluorine; Z¹ is independently asingle bond, ethylene, methyleneoxy or carbonyloxy; and k is 1, 2 or 3.

-   Item 2. The liquid crystal composition according to item 1, wherein    the first component is at least one compound selected from the group    of compounds represented by formula (1-1) to formula (1-3):

wherein R¹ and R² are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkenyloxyhaving 2 to 11 carbons, or alkenyl having 2 to 12 carbons in whicharbitrary hydrogen is replaced by fluorine.

-   Item. 3. The liquid crystal composition according to item 2, wherein    the first component is at least one compound selected from the group    of compounds represented by formula (1-1).-   Item. 4. The liquid crystal composition according to item 2, wherein    the first component is a mixture of at least one compound selected    from the group of compounds represented by formula (1-1) and at    least one compound selected from the group of compounds represented    by formula (1-2).-   Item. 5. The liquid crystal composition according to item 1, wherein    the second component is at least one compound selected from the    group of compounds represented by formula (2-1) to formula (2-7):

wherein R³ and R⁴ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine.

-   Item 6. The liquid crystal composition according to item 5, wherein    the second component is at least one compound selected from the    group of compounds represented by formula (2-1) to formula (2-3).-   Item 7. The liquid crystal composition according to item 5, wherein    the second component is at least one compound selected from the    group of compounds represented by formula (2-4) to formula (2-7).-   Item 8. The liquid crystal composition according to any one of items    1 to 7, wherein the ratio of the first component is in the range of    5% by weight to 40% by weight and the ratio of the second component    is in the range of 5% by weight to 60% by weight, based on the total    weight of the liquid crystal composition.-   Item 9. The liquid crystal composition according to any one of items    1 to 8, further including at least one compound selected from the    group of compounds represented by formula (3) as a third component:

wherein R⁵ and R⁶ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; the ring B and the ring C are independently 1,4-cyclohexylene,1,4-phenylene, 2-fluoro-1,4-phenylene or 3-fluoro-1,4-phenylene; Z² isindependently a single bond, ethylene, methyleneoxy or carbonyloxy; andm is 1, 2 or 3.

-   Item 10. The liquid crystal composition according to item 9, wherein    the third component is at least one compound selected from the group    of compounds represented by formula (3-1) to formula (3-11):

wherein R⁵ and R⁶ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine.

-   Item 11. The liquid crystal composition according to item 10,    wherein the third component is at least one compound selected from    the group of compounds represented by formula (3-1).-   Item 12. The liquid crystal composition according to item 10,    wherein the third component is a mixture of at least one compound    selected from the group of compounds represented by formula (3-1)    and at least one compound selected from the group of compounds    represented by formula (3-4).-   Item 13. The liquid crystal composition according to item 10,    wherein the third component is a mixture of at least one compound    selected from the group of compounds represented by (3-6) and at    least one compound selected from the group of compounds represented    by formula (3-11).-   Item 14. The liquid crystal composition according to any one of    items 9 to 13, wherein the ratio of the third component is in the    range of 10% by weight to 65% by weight based on the total weight of    the liquid crystal composition.-   Item 15. The liquid crystal composition according to any one of    items 1 to 14, further including at least one compound selected from    the group of compounds represented by formula (4) as a fourth    component:

wherein R⁷ and R⁸ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; the ring D is independently 1,4-cyclohexylene or1,4-phenylene; Z³ is independently a single bond, ethylene, methyleneoxyor carbonyloxy; X⁵ and X⁶ are independently fluorine or chlorine; and nis 1, 2 or 3.

-   Item 16. The liquid crystal composition according to item 15,    wherein the fourth component is at least one compound selected from    the group of compounds represented by formula (4-1) to formula    (4-9):

wherein R⁷ and R⁸ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine.

-   Item 17. The liquid crystal composition according to item 16,    wherein the fourth component is at least one compound selected from    the group of compounds represented by formula (4-1).-   Item 18. The liquid crystal composition according to item 16,    wherein the fourth component is a mixture of at least one compound    selected from the group of compounds represented by formula (4-1)    and at least one compound selected from the group of compounds    represented by formula (4-7).-   Item 19. The liquid crystal composition according to any one of    items 15 to 18, wherein the ratio of the fourth component is in the    range of 5% by weight to 50% by weight based on the total weight of    the liquid crystal composition.-   Item 20. The liquid crystal composition according to any one of    items 1 to 19, wherein the maximum temperature of a nematic phase is    70° C. or higher, the optical anisotropy (25° C.) at a wavelength of    589 nanometers is 0.08 or more, and the dielectric anisotropy (25°    C.) at a frequency of 1 kHz is −2 or less.-   Item 21. A liquid crystal display device containing the liquid    crystal composition according to any one of items 1 to 20.-   Item 22. The liquid crystal display device according to item 21,    wherein an operating mode of the liquid crystal display device is a    VA mode, an IPS mode or a PSA mode, and a driving mode of the liquid    crystal display device is an active matrix mode.

The invention further includes the following items: (1) the compositiondescribed above that further includes an optically active compound; (2)the composition described above that further includes an additive, suchas an antioxidant, an ultraviolet light absorber and an antifoamingagent; (3) an AM device that contains the composition described above;(4) a device having a mode of TN, ECB, OCB, IPS, VA or PSA andcontaining the composition described above; (5) a transmission-typedevice that contains the composition described above; (6) use of thecomposition described above as a composition having a nematic phase; and(7) use of an optically active composition prepared by the addition ofan optically active compound to the composition described above.

The composition of the invention will be explained in the followingorder. First, the constitution of component compounds in the compositionwill be explained. Second, main characteristics of the componentcompounds and main effects of these compounds on the composition will beexplained. Third, a combination of components in the composition,desirable ratios of the component compounds and the basis thereof willbe explained. Fourth, a desirable embodiment of the component compoundswill be explained. Fifth, specific examples of the component compoundswill be shown. Sixth, additives that may be mixed with the compositionwill be explained. Seventh, methods for synthesizing the componentcompounds will be explained. Last, use of the composition will beexplained.

First, the constitution of component compounds in the composition willbe explained. The compositions of the invention are classified into thecomposition A and the composition B. The composition A may furtherinclude any other liquid crystal compound, an additive and an impurity.“Any other liquid crystal compound” is a liquid crystal compound that isdifferent from the compound (1), the compound (2), the compound (3) andthe compound (4). Such a compound is mixed with the composition for thepurpose of further adjusting characteristics of the composition. Of anyother liquid crystal compound, a smaller amount of a cyano compound isdesirable in view of its stability to heat or ultraviolet light. A moredesirable ratio of the cyano compound is 0% by weight. The additiveincludes an optically active compound, an antioxidant, an ultravioletlight absorber, a coloring matter, an antifoaming agent, a polymerizablecompound and a polymerization initiator. The impurity is compounds andso forth which have contaminated component compounds in a process suchas their synthesis. Even in the case where the compound is liquidcrystalline, it is classified into an impurity herein.

The composition B consists essentially of compounds selected from thegroup of the compound (1), the compound (2), the compound (3) and thecompound (4). The term “essentially” means that the composition mayinclude an additive and an impurity, but does not include any liquidcrystal compound other than these compounds. The composition B has asmaller number of components than the composition A. The composition Bis preferable to the composition A in view of cost reduction. Thecomposition A is preferable to the composition B in view of the factthat physical properties can be further adjusted by adding any otherliquid crystal compound.

Second, main characteristics of the component compounds and main effectsof the compounds on the characteristics of the composition will beexplained. The main characteristics of the component compounds aresummarized in Table 2 on the basis of the effects of the invention. InTable 2, the symbol L stands for “large” or “high”, the symbol M standsfor “medium”, and the symbol S stands for “small” or “low.” The symbolsL, M and S are classified according to a qualitative comparison amongthe component compounds, and 0 (zero) means that “a value is nearlyzero.”

TABLE 2 Characteristics of Compounds Compounds Compound (1) Compound (2)Compound (3) Compound (4) Maximum Temperature M S-L M-L M-L ViscosityM-L M-L S-M M-L Optical Anisotropy M M-L S-L M-L Dielectric AnisotropyM-L ¹⁾ M-L ¹⁾ 0 M ¹⁾ Specific Resistance L L L L ¹⁾ Value of opticalanisotropy is negative, and the symbol expresses the magnitude of theabsolute value.

Main effects of the component compounds on the characteristics of thecomposition upon mixing the component compounds with the composition areas follows. The compound (1) increases the absolute value of thedielectric anisotropy. The compound (2) increases the absolute value ofthe dielectric anisotropy, or decreases the minimum temperature. Thecompound (3) decreases the viscosity, adjusts the optical anisotropysuitably, increases the maximum temperature, or decreases the minimumtemperature. The compound (4) increases the absolute value of thedielectric anisotropy, and decreases the minimum temperature.

Third, a combination of the components in the composition, desirableratios of the component compounds and the basis thereof will beexplained. A combination of the components in the composition is thefirst and second components, the first, second and third components, thefirst, second and fourth components and the first, second, third andfourth components.

A desirable combination of the components in the composition is thefirst and second components for increasing the absolute value of thedielectric anisotropy, the first, second and third components fordecreasing the viscosity or for increasing the maximum temperature, andthe first, second, third and fourth components for increasing theabsolute value of the dielectric anisotropy or for increasing themaximum temperature.

A desirable ratio of the first component is 5% by weight or more forincreasing the absolute value of the dielectric anisotropy, and 40% byweight or less for decreasing the minimum temperature. A more desirableratio is in the range of 5% by weight to 25% by weight. An especiallydesirable ratio is in the range of 5% by weight to 15% by weight.

A desirable ratio of the second component is 5% by weight or more fordecreasing the viscosity, and 60% by weight or less for increasing themaximum temperature. A more desirable ratio is in the range of 10% byweight to 30% by weight for decreasing the viscosity.

A desirable ratio of the third component is 10% by weight or more fordecreasing the viscosity, and 80% by weight or less for decreasing theminimum temperature. A more desirable ratio is in the range of 15% byweight to 65% by weight. An especially desirable ratio is in the rangeof 20% by weight to 60% by weight.

A desirable ratio of the fourth component is 5% by weight or more forincreasing the absolute value of the dielectric anisotropy, and 40% byweight or less for decreasing the minimum temperature. A more desirableratio is in the range of 10% by weight to 40% by weight. An especiallydesirable ratio is in the range of 15% by weight to 35% by weight.

Fourth, a desirable embodiment of the component compounds will beexplained. R¹ and R² are independently alkyl having 1 to 12 carbons,alkoxy having 1 to 12 carbons, alkenyl having 2 to 12 carbons,alkenyloxy having 2 to 11 carbons, or alkenyl having 2 to 12 carbons inwhich arbitrary hydrogen is replaced by fluorine, and R³, R⁴, R⁵, R⁶, R⁷and R⁸ are independently alkyl having 1 to 12 carbons, alkoxy having 1to 12 carbons, alkenyl having 2 to 12 carbons, or alkenyl having 2 to 12carbons in which arbitrary hydrogen is replaced by fluorine.

Desirable R¹, R², R⁴ and R⁸ are each alkyl having 1 to 12 carbons oralkenyl having 2 to 12 carbons for decreasing the minimum temperatureand for decreasing the viscosity, and alkoxy having 1 to 12 carbons forincreasing the absolute value of the dielectric anisotropy.

Desirable R³, R⁵, R⁶ and R⁷ are each alkyl having 1 to 12 carbons oralkenyl having 2 to 12 carbons for decreasing the minimum temperatureand for decreasing the viscosity. More desirable R¹, R², R³, R⁴, R⁵, R⁶,R⁷ and R⁸ are alkyl having 1 to 12 carbons for increasing the stabilityto ultraviolet light or heat, for instance.

Desirable alkyl is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptylor octyl. More desirable alkyl is ethyl, propyl, butyl, pentyl or heptylfor decreasing the viscosity.

Desirable alkoxy is methoxy, ethoxy, propoxy, butoxy, pentyloxy,hexyloxy or heptyloxy. More desirable alkoxy is methoxy or ethoxy fordecreasing the viscosity.

Desirable alkenyl is vinyl, 1-propenyl, 2-propenyl, 1-butenyl,2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 4-pentenyl,1-hexenyl, 2-hexenyl, 3-hexenyl, 4-hexenyl or 5-hexenyl. More desirablealkenyl is vinyl, 1-propenyl, 3-butenyl or 3-pentenyl for decreasing theviscosity. A desirable configuration of —CH═CH— in the alkenyl dependson the position of the double bond. Trans is preferable in the alkenylsuch as 1-propenyl, 1-butenyl, 1-pentenyl, 1-hexenyl, 3-pentenyl and3-hexenyl for decreasing the viscosity for instance. Cis is preferablein the alkenyl such as 2-butenyl, 2-pentenyl and 2-hexenyl. In thealkenyl, straight-chain alkenyl is preferable to branched-chain alkenyl.

Desirable alkenyloxy is vinyloxy, allyloxy, 3-butenyloxy, 3-pentenyloxyor 4-pentenyloxy. More desirable alkenyloxy is allyloxy or 3-butenyloxyfor decreasing the viscosity.

Desirable examples of alkenyl in which arbitrary hydrogen is replaced byfluorine are 2,2-difluorovinyl, 3,3-difluoro-2-propenyl,4,4-difluoro-3-butenyl, 5,5-difluoro-4-pentenyl and6,6-difluoro-5-hexenyl. More desirable examples are 2,2-difluorovinyland 4,4-difluoro-3-butenyl for decreasing the viscosity.

The ring A is independently

and at least one of the rings A is

and arbitrary two of the ring A may be the same or different when k is 2or 3. Desirable ring A is

for increasing the absolute value of the dielectric anisotropy,1,4-cyclohexylene for increasing the maximum temperature, and1,4-phenylene for increasing refractive index anisotropy. The ring B andthe ring C are independently 1,4-cyclohexylene, 1,4-phenylene,2-fluoro-1,4-phenylene or 3-fluoro-1,4-phenylene, and arbitrary two ofthe ring B may be the same or different when m is 2 or 3. Desirable ringB and ring C are each 1,4-cyclohexylene for increasing the maximumtemperature or for decreasing the viscosity, and 1,4-phenylene forincreasing the optical anisotropy. The ring D is independently1,4-cyclohexylene or 1,4-phenylene, and arbitrary two of the ring D maybe the same or different when n is 2 or 3. Desirable ring D is1,4-cyclohexylene for increasing the maximum temperature or fordecreasing the viscosity, and 1,4-phenylene for increasing the opticalanisotropy.

X¹, X², X³ and X⁴ are independently hydrogen, fluorine or chlorine, andat least three of X¹, X², X³ and X⁴ is fluorine. Desirable X¹, X², X³and X⁴ is fluorine for decreasing the viscosity. X⁵ and X⁶ areindependently fluorine or chlorine. Desirable X⁵ and X⁶ are fluorine fordecreasing the viscosity.

Z¹ is independently a single bond, ethylene, methyleneoxy orcarbonyloxy, and arbitrary two of Z¹ may be the same or different when kis 2 or 3. Desirable Z¹ is a single bond for decreasing the viscosity.Z² is independently a single bond, ethylene, methyleneoxy orcarbonyloxy, and arbitrary two of Z² may be the same or different when mis 2 or 3. Desirable Z² is a single bond for decreasing the viscosity.Z³ is independently a single bond, ethylene, methyleneoxy orcarbonyloxy, and arbitrary two of Z³ may be the same or different when nis 2 or 3. Desirable Z³ is ethylene for decreasing the minimumtemperature and a single bond for decreasing the viscosity.

k is 1, 2 or 3. Desirable k is 2 or 3 for increasing the maximumtemperature. m is 1, 2 or 3. Desirable m is 1 or 2 for decreasing theminimum temperature or for decreasing the viscosity, and is 3 forincreasing the maximum temperature. n is 1, 2 or 3. Desirable n is 2 or3 for increasing the maximum temperature, and is 1 for decreasing theviscosity.

Fifth, specific examples of the component compounds will be shown. Inthe desirable compounds described below, R⁹ and R¹⁰ are independentlystraight-chain alkyl having 1 to 12 carbons, alkoxy having 1 to 12carbons, straight-chain alkenyloxy having 2 to 11 carbons andstraight-chain alkenyl having 2 to 12 carbons; and R¹¹ and R¹² areindependently straight-chain alkyl having 1 to 12 carbons, alkoxy having1 to 12 carbons and straight-chain alkenyl having 2 to 12 carbons. Withregard to the configuration of 1,4-cyclohexylene in these compounds,trans is preferable to cis for increasing the maximum temperature.

Desirable compound (1) are the compound (1-1-1) to the compound (1-3-1).More desirable compound (1) are the compound (1-1-1) and the compound(1-2-1). Desirable compound (2) are the compound (2-1-1) to the compound(2-7-1). More desirable compound (2) are the compound (2-1-1) and thecompound (2-4-1) to the compound (2-7-1). Especially desirable compound(2) are the compound (2-4-1), the compound (2-5-1) and the compound(2-7-1). Desirable compound (3) are the compound (3-1-1) to the compound(3-11-1). More desirable compound (3) are the compound (3-1-1) to thecompound (3-4-1) and the compound (3-6-1) to the compound (3-11-1).Especially desirable compound (3) are the compound (3-1-1), the compound(3-4-1), the compound (3-6-1) and the compound (3-11-1). Desirablecompound (4) are the compound (4-1-1) to the compound (4-9-1). Moredesirable compound (4) are the compound (4-1-1) to the compound (4-7-1).Especially desirable compound (4) are the compound (4-1-1), the compound(4-4-1) and the compound (4-7-1).

Sixth, additives which may be mixed with the composition will beexplained. Such additives include an optically active compound, anantioxidant, an ultraviolet light absorber, a coloring matter, anantifoaming agent, a polymerizable compound and a polymerizationinitiator. The optically active compound is mixed with the compositionfor the purpose of inducing a helical structure and giving a twist anglein liquid crystals. Examples of such compounds include the compound(5-1) to the compound (5-4). A desirable ratio of the optically activecompound is 5% by weight or less, and a more desirable ratio is in therange of 0.01% by weight to 2% by weight.

An antioxidant is mixed with the composition in order to prevent adecrease in specific resistance that is caused by heating under air, orto maintain a large voltage holding ratio at room temperature and alsoat a high temperature after the device has been used for a long time.

Desirable examples of the antioxidant include the compound (6) where wis an integer from 1 to 9. In the compound (6), desirable w is 1, 3, 5,7 or 9. More desirable w is 1 or 7. The compound (6) where w is 1 iseffective in preventing a decrease in specific resistance that is causedby heating under air because it has a large volatility. The compound (6)where w is 7 is effective in maintaining a large voltage holding ratioat room temperature and also at a high temperature even after the devicehas been used for a long time, because it has a small volatility. Adesirable ratio of the antioxidant is 50 ppm or more for achieving itseffect and is 600 ppm or less for avoiding a decrease in the maximumtemperature or avoiding an increase in the minimum temperature. A moredesirable ratio is in the range of 100 ppm to 300 ppm.

Desirable examples of the ultraviolet light absorber include abenzophenone derivative, a benzoate derivative and a triazolederivative. A light stabilizer such as an amine having steric hindranceis also desirable. A desirable ratio of the ultraviolet light absorberor the light stabilizer is 50 ppm or more for achieving its effect andis 10,000 ppm or less for avoiding a decrease in the maximum temperatureor avoiding an increase in the minimum temperature. A more desirableratio is in the range of 100 ppm to 10,000 ppm.

A dichroic dye such as an azo dye or an anthraquinone dye is mixed withthe composition for adjusting to a device having a guest host (GH) mode.A desirable ratio of the coloring matter is in the range of 0.01% byweight to 10% by weight. An antifoaming agent such as dimethyl siliconeoil or methyl phenyl silicone oil is mixed with the composition forpreventing foam formation. A desirable ratio of the antifoaming agent is1 ppm or more for achieving its effect and is 1,000 ppm or less foravoiding a poor display. A more desirable ratio is in the range of 1 ppmto 500 ppm.

A polymerizable compound is mixed with the composition for adjusting toa device having a polymer sustained alignment (PSA) mode. Desirableexamples of the polymerizable compound include compounds having apolymerizable group, such as acrylates, methacrylates, vinyl compounds,vinyloxy compounds, propenyl ethers, epoxy compounds (oxiranes,oxetanes) and vinyl ketones. Especially desirable examples of thepolymerizable compound are acrylate derivatives or methacrylatederivatives. A desirable ratio of the polymerizable compound is 0.05% byweight or more for achieving its effect and is 10% by weight or less foravoiding a poor display. A more desirable ratio is in the range of 0.1%by weight to 2% by weight. The polymerizable compound is polymerized onirradiation with ultraviolet light or the like, preferably in thepresence of a suitable initiator such as a photopolymerizationinitiator. Suitable conditions for polymerization, suitable types of theinitiator and suitable amounts thereof are known to a person skilled inthe art and are described in the literature. For example, Irgacure 651(registered trademark), Irgacure 184 (registered trademark) or Darocure1173 (registered trademark) (Ciba Japan K.K.), each of which is aphotopolymerization initiator, is suitable for radical polymerization.The polymerizable compound includes the photopolymerization initiatorpreferably in the range of 0.1% by weight to 5% by weight and mostpreferably in the range of 1% by weight to 3% by weight.

Seventh, methods for synthesizing the component compounds will beexplained. These compounds can be synthesized by known methods. Thesynthetic methods will be exemplified as follows. The compound (1-1) isprepared by the method described in JP H09-052852 A (1997). The compound(2-5) is prepared by the method described in JP 2000-008040 A (2000).The compound (3-1) is prepared by the method described in JP H04-030382B (1992). The compound (3-4) is prepared by the method described in JPS57-165328 A (1982). The compound (4-1) is prepared by the methoddescribed in JP 2000-053602 A (2000). An antioxidant is commerciallyavailable. The compound where w is 1 in formula (6) is available fromSigma-Aldrich Corporation. The compound (6) where w is 7, and so forthare synthesized according to the method described in U.S. Pat. No.3,660,505.

Compounds whose synthetic methods are not described above can beprepared according to the methods described in books such as OrganicSyntheses (John Wiley & Sons, Inc.), Organic Reactions (John Wiley &Sons, Inc.), Comprehensive Organic Synthesis (Pergamon Press), Newexperimental Chemistry Course (Shin Jikken Kagaku Kouza, in Japanese;Maruzen Co., Ltd.). The composition is prepared according to knownmethods using the compounds thus obtained. For example, the componentcompounds are mixed and dissolved each other by heating.

Last, use of the composition will be explained. Most of the compositionsof the invention have a minimum temperature of −10° C. or lower, amaximum temperature of 70° C. or higher, and an optical anisotropy inthe range of 0.07 to 0.20. A device containing this composition has alarge voltage holding ratio. The composition is suitable for an AMdevice. The composition is suitable especially for an AM device having atransmission type. The composition having an optical anisotropy in therange of 0.08 to 0.25 may be prepared by adjusting ratios of thecomponent compounds or by mixing with any other liquid crystal compound.The composition can be used as a composition having a nematic phase, oras an optically active composition by the addition of an opticallyactive compound.

The composition can be used for an AM device. It can also be used for aPM device. The composition can also be used for the AM device and the PMdevice having a mode such as PC, TN, STN, ECB, OCB, IPS, VA or PSA. Itis especially desirable to use the composition for the AM device havingthe IPS or VA mode. These devices may be of a reflection type, atransmission type or a semi-transmission type. It is desirable to usethe composition for a device having the transmission type. It can beused for an amorphous silicon-TFT device or a polycrystal silicon-TFTdevice. The composition is also usable for a nematic curvilinear alignedphase (NCAP) device prepared by microcapsulating the composition, andfor a polymer dispersed (PD) device in which a three-dimensionalnetwork-polymer is formed in the composition.

EXAMPLES

When a sample was a composition, it was measured as it was, and thevalue obtained was described here. When a sample was a compound, asample for measurement was prepared by mixing 15% by weight of thecompound and 85% by weight of mother liquid crystals. The characteristicvalues of the compound were calculated from values obtained bymeasurement, according to a method of extrapolation. That is:(extrapolated value)=[(measured value of a sample)−0.85×(measured valueof mother liquid crystals)]/0.15. When a smectic phase (or crystals)separated out in this ratio at 25° C., the ratio of the compound to themother liquid crystals was changed step by step in the order of (10% byweight/90% by weight), (5% by weight/95% by weight) and (1% byweight/99% by weight). Values of the maximum temperature, the opticalanisotropy, the viscosity and the dielectric anisotropy with regard tothe compound were obtained by this extrapolation method.

The components of the mother liquid crystals were as follows. The ratioswere expressed as a percentage by weight.

Characteristics were measured according to the following methods. Mostmethods are described in the Standards of Electronic IndustriesAssociation of Japan, EIAJ-ED-2521 A or those with some modifications.

Maximum Temperature of a Nematic Phase (NI; ° C.): A sample was placedon a hot plate in a melting point apparatus equipped with a polarizingmicroscope and was heated at the rate of 1° C. per minute. Thetemperature was measured when part of the sample began to change from anematic phase to an isotropic liquid. A higher limit of the temperaturerange of a nematic phase may be abbreviated to “the maximumtemperature.”

Minimum Temperature of a Nematic Phase (Tc; ° C.): A sample having anematic phase was put in glass vials and then kept in freezers attemperatures of 0° C., −10° C., −20° C., −30° C. and −40° C. for 10days, and then the liquid crystal phases were observed. For example,when the sample maintained the nematic phase at −20° C. and changed tocrystals or a smectic phase at −30° C., Tc was expressed as −20° C. Alower limit of the temperature range of a nematic phase may beabbreviated to “the minimum temperature.”

Viscosity (bulk viscosity; η;measured at 20° C.; mPa·s): Viscosity wasmeasured by use of an E-type viscometer.

Optical Anisotropy (refractive index anisotropy; Δn; measured at 25°C.): Measurement was carried out by use of an Abbe refractometer with apolarizing plate mounted on the ocular, using light at a wavelength of589 nanometers. The surface of the main prism was rubbed in onedirection, and then a sample was dropped on the main prism. A refractiveindex (n∥) was measured when the direction of polarized light wasparallel to that of the rubbing. A refractive index (n⊥) was measuredwhen the direction of polarized light was perpendicular to that of therubbing. The value of optical anisotropy was calculated from theequation: Δn=n∥−n⊥.

Dielectric Anisotropy (Δ∈; measured at 25° C.): The value of dielectricanisotropy was calculated from the equation: Δ∈=∈∥−∈⊥. Dielectricconstants (∈∥ and ∈⊥) were measured as follows.

-   1) Measurement of a dielectric constant (∈∥): A solution of    octadecyltriethoxysilane (0.16 mL) in ethanol (20 mL) was applied to    a thoroughly cleaned glass substrate. The glass substrate was    rotated with a spinner, and then heated at 150° C. for one hour. A    sample was poured into a VA device in which the distance between the    two glass substrates (cell gap) was 4 micrometers, and then the    device was sealed with an adhesive curable on irradiation with    ultraviolet light. Sine waves (0.5 V, 1 kHz) were applied to the    device, and a dielectric constant (∈∥) in the major axis direction    of liquid crystal molecules was measured after 2 seconds.-   2) Measurement of a dielectric constant (∈⊥): A polyimide solution    was applied to a thoroughly cleaned glass substrate. The glass    substrate was burned, and then the resulting alignment film was    subjected to rubbing treatment. A sample was poured into a TN device    in which the distance between the two glass substrates (cell gap)    was 9 micrometers and the twist angle was 80 degrees. Sine waves    (0.5 V, 1 kHz) were applied to the device, and a dielectric constant    (∈⊥) in the minor axis direction of liquid crystal molecules was    measured after 2 seconds.

Threshold Voltage (Vth; measured at 25° C.; V): Measurement was carriedout with an LCD evaluation system Model LCD-5100 made by OtsukaElectronics Co., Ltd. The light source was a halogen lamp. A sample waspoured into a VA device having a normally black mode, in which thedistance between the two glass substrates (cell gap) was 4 micrometersand the rubbing direction was antiparallel, and then the device wassealed with an adhesive curable on irradiation with ultraviolet light.Voltage to be applied to the device (60 Hz, rectangular waves) wasstepwise increased in 0.02 V increments from 0 V up to 20 V. During theincrease, the device was irradiated with light in the perpendiculardirection, and the amount of light passing through the device wasmeasured. A voltage-transmittance curve was prepared, in which themaximum amount of light corresponded to 100% transmittance and theminimum amount of light corresponded to 0% transmittance. The thresholdvoltage was voltage at 10% transmittance.

Voltage Holding Ratio (VHR-1; measured at 25° C.; %): A TN device usedfor measurement had a polyimide-alignment film, and the distance betweenthe two glass substrates (cell gap) was 5 micrometers. A sample waspoured into the device, and then the device was sealed with aUV-polymerizable adhesive. A pulse voltage (60 microseconds at 5 V) wasapplied to the TN device and the device was charged. A decreasingvoltage was measured for 16.7 milliseconds with a high-speed voltmeter,and the area A between the voltage curve and the horizontal axis in aunit cycle was obtained. The area B was an area without the decrease.The voltage holding ratio was the percentage of the area A to the areaB.

Voltage Holding Ratio (VHR-2; measured at 80° C.; %): A TN device usedfor measurement had a polyimide-alignment film, and the distance betweenthe two glass substrates (cell gap) was 5 micrometer. A sample waspoured into the device, and then the device was sealed with aUV-polymerizable adhesive. A pulse voltage (60 microseconds at 5 V) wasapplied to the TN device and the device was charged. A decreasingvoltage was measured for 16.7 milliseconds with a high-speed voltmeterand the area A between the voltage curve and the horizontal axis in aunit cycle was obtained. The area B was an area without the decrease.The voltage holding ratio was a percentage of the area A to the area B.

Voltage Holding Ratio (VHR-3; measured at 25° C.; %): The stability toultraviolet light was evaluated by measuring a voltage holding ratioafter irradiation with ultraviolet light. A composition having a largeVHR-3 has a high stability to ultraviolet light. A TN device used formeasurement had a polyimide-alignment film and the cell gap was 5micrometers. A sample was poured into this device, and then the devicewas irradiated with light for 20 minutes. The light source was an ultrahigh-pressure mercury lamp USH-500D (produced by Ushio, Inc.), and thedistance between the device and the light source was 20 centimeters. Inthe measurement of VHR-3, a decreasing voltage was measured for 16.7milliseconds. The value of VHR-3 is preferably 90% or more, and morepreferably 95% or more.

Voltage Holding Ratio (VHR-4; measured at 25° C.; %): A TN device intowhich a sample was poured was heated in a constant-temperature bath at80° C. for 500 hours, and then the stability to heat was evaluated bymeasuring the voltage holding ratio. A composition having a large VHR-4has a high stability to heat. In the measurement of VHR-4, a decreasingvoltage was measured for 16.7 milliseconds.

Response Time (τ; measured at 25° C.; millisecond): Measurement wascarried out with an LCD evaluation system Model LCD-5100 made by OtsukaElectronics Co., Ltd. The light source was a halogen lamp. The low-passfilter was set at 5 kHz. A sample was poured into a VA device having anormally black mode, in which the cell gap between the two glasssubstrates was 4 micrometers, and the rubbing direction wasantiparallel, and then the device was sealed with a UV curable adhesive.Rectangular waves (60 Hz, 10 V, 0.5 second) were applied to the device.The device was simultaneously irradiated with light in the perpendiculardirection, and the amount of light passing through the device wasmeasured. The maximum amount of light corresponded to 100%transmittance, and the minimum amount of light corresponded to 0%transmittance. The response time was the period of time required for thechange from 90% to 10% transmittance (fall time; millisecond).

Specific Resistance (ρ; measured at 25° C.; Ωcm): A sample of 1.0milliliter was poured into a vessel equipped with electrodes. DC voltage(10 V) was applied to the vessel, and the DC current was measured after10 seconds. The specific resistance was calculated from the followingequation. (specific resistance)=[(voltage)×(electric capacity ofvessel)]/[(DC current)×(dielectric constant in vacuum)].

Gas Chromatographic Analysis: A gas chromatograph Model GC-14B made byShimadzu Corporation was used for measurement. The carrier gas washelium (2 milliliters per minute). The sample injector and the detector(FID) were set to 280° C. and 300° C., respectively. A capillary columnDB-1 (length 30 meters, bore 0.32 millimeter, film thickness 0.25micrometer, dimethylpolysiloxane as the stationary phase, non-polar)made by Agilent Technologies, Inc. was used for the separation ofcomponent compounds. After the column had been kept at 200° C. for 2minutes, it was further heated to 280° C. at the rate of 5° C. perminute. A sample was dissolved in acetone (0.1% by weight), and 1microliter of the solution was injected into the sample injector. Arecorder used was a Model C-R5A Chromatopac Integrator made by ShimadzuCorporation or its equivalent. The resulting gas chromatogram showed theretention time of peaks and the peak areas corresponding to thecomponent compounds.

Solvents for diluting the sample may also be chloroform, hexane and soforth. The following capillary columns may also be used in order toseparate the component compounds: HP-1 made by Agilent Technologies Inc.(length 30 meters, bore 0.32 millimeter, film thickness 0.25micrometer), Rtx-1 made by Restek Corporation (length 30 meters, bore0.32 millimeter, film thickness 0.25 micrometer), and BP-1 made by SGEInternational Pty. Ltd. (length 30 meters, bore 0.32 millimeter, filmthickness 0.25 micrometer). A capillary column CBP1-M50-025 (length 50meters, bore 0.25 millimeter, film thickness 0.25 micrometer) made byShimadzu Corporation may also be used for the purpose of avoiding anoverlap of peaks of the compounds.

The ratio of the liquid crystal compounds included in the compositionmay be calculated according to the following method. The liquid crystalcompounds are detected by use of a gas chromatograph. The ratio of peakareas in the gas chromatogram corresponds to the ratio (molar ratio) ofthe liquid crystal compounds. When the capillary columns described aboveare used, the correction coefficient of respective liquid crystalcompounds may be regarded as 1 (one). Accordingly, the ratio (percentageby weight) of the liquid crystal compounds can be calculated from theratio of peak areas.

The invention will be explained in detail by way of Examples. Theinvention is not limited by Examples described below. The compoundsdescribed in Comparative Examples and Examples were expressed as symbolsaccording to the definition in the following Table 3. In Table 3, theconfiguration of 1,4-cyclohexylene is trans. A parenthesized number nextto the symbolized compound in Example corresponds to the number of adesirable compound. The symbol (−) means any other liquid crystalcompound. Ratios (percentage) of liquid crystal compounds mean thepercentages by weight (% by weight) based on the total weight of theliquid crystal composition. The liquid crystal composition furtherincludes an impurity. Last, characteristics of the composition aresummarized.

TABLE 3 Method of Description of Compounds using SymbolsR-(A₁)-Z₁-...-Z_(n)-(A_(n))-R′ 1) Left-terminal Group R- SymbolC_(n)H_(2n+1)— n- C_(n)H_(2n+1)O— nO— C_(m)H_(2m+1)OC_(n)H_(2n)— mOn-CH₂═CH— V— C_(n)H_(2n+1)—CH═CH— nV— CH₂═CH—C_(n)H_(2n)— Vn-C_(m)H_(2m+1)—CH═CH—C_(n)H_(2n)— mVn- CF₂═CH— VFF— CF₂═CH—C_(n)H_(2n)—VFFn- 2) Right-terminal Group -R′ Symbol —C_(n)H_(2n+1) -n—OC_(n)H_(2n+1) —On —CH═CH₂ —V —CH═CH—C_(n)H_(2n+1) —Vn—C_(n)H_(2n)—CH═CH₂ -nV —CH═CF₂ —VFF —COOCH₃ -EMe 3) Bonding Group-Z_(n)- Symbol —OC_(n)H_(2n)O— OnO —C_(n)H_(2n)— n —COO— E —CH═CH— V—CH₂O— 1O —OCH₂— O1 —SiH₂— Si —CF₂O— CF2O —OCF₂— OCF2 4) Ring Structure-A_(n)- Symbol

H

Ch

ch

Dh

dh

B

B(2F)

B(3F)

B(2F,3F)

B(2F,3CL)

B(2CL,3F) 5) Examples of Description

Comparative Example 1

Example 1 was selected from the compositions disclosed in JP 2001-316669A. The basis of the selection was that this composition included thecompound (1-1-1), the compound (3-1-1), the compound (4-1-1) and thecompound (4-4-1). The composition was prepared and measured according tothe method described above. The components and characteristics of thecomposition were as follows:

2O-B(2F,3F)B(2F,3F)-O3 (1-1-1) 8% 5-HH-V (3-1-1) 5% 3-HB(2F,3F)-O4(4-1-1) 9% 5-HB(2F,3F)-O4 (4-1-1) 9% 2-HHB(2F,3F)-O2 (4-4-1) 9%3-HHB(2F,3F)-O2 (4-4-1) 10% 5-HHB(2F,3F)-O2 (4-4-1) 9% 2-HHB(2F,3F)-1(4-4-1) 11% 3-HHB(2F,3F)-1 (4-4-1) 10% 3O-HHB(2F,3F)-O2 (4-4-1) 10%V1O-HHB(2F,3F)-O2 (—) 10% NI = 101.3° C.; Δn = 0.098; η = 56.3 mPa · s;Δε = −6.6.

Comparative Example 2

Example 1 was selected from the compositions disclosed in US2005/0104039 A. The basis of the selection was that the compositionincluded the compound (1-1-1), the compound (3-2-1), the compound(3-5-1), the compound (4-1-1), the compound (4-4-1) and the compound(4-7-1). The composition was prepared and measured according to themethod described above. The components and characteristics of thecomposition were as follows:

4-B(2F,3F)B(2F,3F)-O2 (1-1-1) 6% 3-HB-O1 (3-2-1) 2% 3-HBB-2 (3-5-1) 7%3-HB(2F,3F)-O4 (4-1-1) 6% 5-HB(2F,3F)-O2 (4-1-1) 6% 5-HB(2F,3F)-O4(4-1-1) 10% 3-HHB(2F,3F)-O2 (4-4-1) 3% 5-HHB(2F,3F)-O2 (4-4-1) 4%2-HBB(2F,3F)-O2 (4-7-1) 14% 3-HBB(2F,3F)-O2 (4-7-1) 12%5-ChB(2F)B(2F,3F)-O2 (—) 15% 5-H2BB(2F,3F)-O2 (4) 15% NI = 98.9° C.; Δn= 0.149; η = 65.8 mPa · s; Δε = −6.6.

Comparative Example 3

Example 7 was selected from the compositions disclosed in JP 2001-262145A. The basis of the selection was that the composition included thecompound (2-1-1), the compound (2-5-1), the compound (3-1-1) and thecompound (3-2-1), and had the highest maximum temperature. Thecomponents and characteristics of the composition were as follows:

3-H1SiB(2F,3F)-O2 (—) 5% 3-HH1SiB(2F,3F)-O2 (—) 4% 3-DhB(2F,3F)-O2(2-1-1) 5% 3-HDhB(2F,3F)-O2 (2-5-1) 12% 5-HDhB(2F,3F)-O2 (2-5-1) 8%3-BDhB(2F,3F)-O2 (2) 5% 5-BDhB(2F,3F)-O2 (2) 5% 3-DhB(2F,3F)B(2F,3F)-O2(—) 4% 5-HHCF2OB(2F,3F)-O2 (—) 5% 5-HBCF2OB(2F,3F)-O2 (—) 6%3-HCF2OHB(2F,3F)-O2 (—) 5% 3-HchOCF2B(2F,3F)-O1 (—) 5%3-HCF2OBB(2F,3F)-O2 (—) 5% 3-HBOCF2B (2F,3F)-O1 (—) 5%3-HB(2F,3F)OCF2B(2F,3F)-O1 (—) 5% 3-HH-4 (3-1-1) 8% 3-HB-O2 (3-2-1) 4%3-HH-EMe (—) 4% NI = 94.0° C.; Tc ≦ −20° C.; Δn = 0.099; η = 42.0 mPa ·s; Δε = −4.5.

Comparative Example 4

Example 14 was selected from the compositions disclosed in JP2001-115161 A. The basis of the selection was that the compositionincluded the compound (2-1-1), the compound (2-4-1), the compound(2-5-1), the compound (2-6-1), the compound (3-1-1), the compound(3-2-1) and the compound (3-4-1), and had the highest maximumtemperature. The components and characteristics of the composition wereas follows:

5-DhB(2F,3F)-O1 (2-1-1) 5% 3-DhHB(2F,3F)-O2 (2-4-1) 3% 3-HDhB(2F,3F)-1(2-5-1) 4% 3-HDhB(2F,3F)-3 (2-5-1) 4% 3-HDhB(2F,3F)-O1 (2-5-1) 10%5-HDhB(2F,3F)-O1 (2-5-1) 10% 3-HDhB(2F,3F)-O2 (2-5-1) 11%5-HDhB(2F,3F)-O2 (2-5-1) 11% 3-DhBB(2F,3F)-O2 (2-6-1) 4%3-H2DhB(2F,3F)-O2 (2) 3% 5-BDhB(2F,3F)-O1 (2) 4% 3-HH-4 (3-1-1) 10%3-HB-O2 (3-2-1) 8% 3-HHB-1 (3-4-1) 4% 3-HHB-O1 (3-4-1) 5% 3-HH-EMe (—)4% NI = 96.3° C.; Tc ≦ −20° C.; Δn = 0.095; η = 40.7 mPa · s; Δε = −3.9.

Example 1

2O-B(2F,3F)B(2F,3F)-O6 (1-1-1) 3% 4O-B(2F,3F)B(2F,3F)-O6 (1-1-1) 5%6O-B(2F,3F)B(2F,3F)-O8 (1-1-1) 4% 2-DhHB(2F,3F)-O2 (2-4-1) 4%3-DhHB(2F,3F)-O2 (2-4-1) 5% 5-DhHB(2F,3F)-O2 (2-4-1) 5% 3-HDhB(2F,3F)-O2(2-5-1) 6% 5-HDhB(2F,3F)-O2 (2-5-1) 6% 2-HH-3 (3-1-1) 23% 3-HH-5 (3-1-1)5% 3-HH-V1 (3-1-1) 3% 3-HHB-1 (3-4-1) 5% 3-HHB-O1 (3-4-1) 5% 3-HHB-3(3-4-1) 5% V2-HHB-1 (3-4-1) 9% 1O1-HBBH-5 (—) 7% NI = 103.6° C.; Tc ≦−20° C.; Δn = 0.093; η = 27.1 mPa · s; Δε = −2.9; VHR-1 = 99.1%; VHR-2 =97.9%; VHR-3 = 97.6%.

Example 2

3-B(2F,3F)B(2F,3F)-O2 (1-1-1) 3% 4-B(2F,3F)B(2F,3F)-O2 (1-1-1) 3%5-B(2F,3F)B(2F,3F)-O2 (1-1-1) 3% 4O-B(2F,3F)B(2F,3F)-O6 (1-1-1) 3%3-DhHB(2F,3F)-O2 (2-4-1) 4% 4-DhHB(2F,3F)-O2 (2-4-1) 3% 5-DhHB(2F,3F)-O2(2-4-1) 4% 3-HDhB(2F,3F)-O2 (2-5-1) 5% 5-HDhB(2F,3F)-O2 (2-5-1) 7%3-DhBB(2F,3F)-O2 (2-6-1) 5% 2-HH-3 (3-1-1) 6% 3-HH-4 (3-1-1) 5% 3-HH-5(3-1-1) 6% 3-HH-V1 (3-1-1) 7% 3-HHB-1 (3-4-1) 8% 3-HHB-O1 (3-4-1) 6%3-HHB-3 (3-4-1) 6% V-HHB-1 (3-4-1) 6% V2-HHB-1 (3-4-1) 10% NI = 103.8°C.; Tc ≦ −20° C.; Δn = 0.099; η = 27.2 mPa · s; Δε = −2.8; VHR-1 =99.2%; VHR-2 = 98.0%; VHR-3 = 97.9%.

Example 3

2O-B(2F,3F)B(2F,3F)-O6 (1-1-1) 2% 4O-B(2F,3F)B(2F,3F)-O6 (1-1-1) 3%6O-B(2F,3F)B(2F,3F)-O8 (1-1-1) 3% 2O-B(2F)B(2F,3F)-O6 (1-2-1) 4%6O-B(2F)B(2F,3F)-O2 (1-2-1) 3% 3-DhHB(2F,3F)-O2 (2-4-1) 5%4-DhHB(2F,3F)-O2 (2-4-1) 3% 5-DhHB(2F,3F)-O2 (2-4-1) 5% 3-HDhB(2F,3F)-O2(2-5-1) 6% 5-HDhB(2F,3F)-O2 (2-5-1) 5% 2-HH-3 (3-1-1) 14% 3-HH-5 (3-1-1)3% 3-HH-V1 (3-1-1) 5% 3-HHB-1 (3-4-1) 8% 3-HHB-O1 (3-4-1) 5% 3-HHB-3(3-4-1) 8% V-HHB-1 (3-4-1) 8% V2-HHB-1 (3-4-1) 10% NI = 103.3° C.; Tc ≦−20° C.; Δn = 0.098; η = 27.2 mPa · s; Δε = −2.7.

Example 4

V2-B(2F,3F)B(2F,3F)-O2 (1-1-1) 3% 2O-B(2F,3F)B(2F,3F)-O6 (1-1-1) 2%4O-B(2F,3F)B(2F,3F)-O6 (1-1-1) 3% V1O-B(2F,3F)B(2F,3F)-O4 (1-1-1) 3%V2O-B(2F,3F)B(2F,3F)-O6 (1-1-1) 3% V1O-B(2F)B(2F,3F)-O4 (1-2-1) 3%V2O-B(2F)B(2F,3F)-O6 (1-2-1) 2% 3-DhHB(2F,3F)-O2 (2-4-1) 3%4-DhHB(2F,3F)-O2 (2-4-1) 3% 5-DhHB(2F,3F)-O2 (2-4-1) 3% 5-HDhB(2F,3F)-O2(2-5-1) 3% 2-HH-3 (3-1-1) 21% 3-HH-5 (3-1-1) 7% 3-HH-V1 (3-1-1) 5%3-HHB-1 (3-4-1) 6% 3-HHB-O1 (3-4-1) 6% 1V-HHB-1 (3-4-1) 7% 2-BB(3F)B-3(3-6-1) 3% 5-HBB(3F)B-2 (3-11-1) 7% 5-HBB(3F)B-3 (3-11-1) 7% NI = 104.1°C.; Tc ≦ −20° C.; Δn = 0.123; η = 27.9 mPa · s; Δε = −2.7.

Example 5

2O-B(2F,3F)B(2F,3F)-O6 (1-1-1) 3% 4O-B(2F,3F)B(2F,3F)-O6 (1-1-1) 4%6O-B(2F,3F)B(2F,3F)-O8 (1-1-1) 3% 2O-B(2F)B(2F,3F)-O6 (1-2-1) 3%2O-B(3F)B(2F,3F)-O2 (1-3-1) 2% 5-DhB(2F,3F)-O2 (2-1-1) 7%3-DhHB(2F,3F)-O2 (2-4-1) 3% 5-DhHB(2F,3F)-O2 (2-4-1) 5% 3-HDhB(2F,3F)-O2(2-5-1) 5% 2-HH-3 (3-1-1) 5% 3-HH-5 (3-1-1) 5% 3-HH-V (3-1-1) 4% 3-HH-V1(3-1-1) 6% 3-HB-O2 (3-2-1) 3% V2-BB-1 (3-3-1) 3% 3-HHB-1 (3-4-1) 7%3-HHB-O1 (3-4-1) 5% V2-HHB-1 (3-4-1) 10% 1-BB(3F)B-2V (3-6-1) 3%3-HHEH-5 (3-7-1) 3% 3-HHEBH-3 (3-8-1) 5% 3-HHEBH-5 (3-8-1) 3%5-HBB(3F)B-2 (3-11-1) 3% NI = 104.5° C.; Tc ≦ −20° C.; Δn = 0.109; η =27.7 mPa · s; Δε = −2.7.

Example 6

2O-B(2F,3F)B(2F,3F)-O8 (1-1-1) 3% 4O-B(2F,3F)B(2F,3F)-O6 (1-1-1) 3%6O-B(2F,3F)B(2F,3F)-O8 (1-1-1) 3% 3-Dh2B(2F,3F)-O4 (2-2-1) 5%3-DhHB(2F,3F)-O2 (2-4-1) 3% V-DhHB(2F,3F)-O2 (2-4-1) 3% 3-HDhB(2F,3F)-O2(2-5-1) 5% 3-HH-V (3-1-1) 30% 3-HHB-1 (3-4-1) 5% 3-HHB-3 (3-4-1) 5%3-HHEBH-3 (3-8-1) 5% 3-HHEBH-5 (3-8-1) 3% 5-HBB(3F)B-3 (3-11-1) 8%V-HB(2F,3F)-O2 (4-1-1) 5% 3-HBB(2F,3F)-O2 (4-7-1) 7% 5-HBB(2F,3F)-O2(4-7-1) 7% NI = 104.0° C.; Tc ≦ −20° C.; Δn = 0.106; η = 24.0 mPa · s;Δε = −2.9.

Example 7

5-B(2F,3F)B(2F,3F)-O2 (1-1-1) 3% 6O-B(2F)B(2F,3F)-O4 (1-2-1) 3%7-B(2F)B(2F,3F)-O2 (1-2-1) 3% 3-DhHB(2F,3F)-O2 (2-4-1) 5%5-DhHB(2F,3F)-O2 (2-4-1) 3% 5-HDhB(2F,3F)-O2 (2-5-1) 3% 5-HH-O1 (3-1-1)3% 3-HH-V (3-1-1) 14% 3-HH-V1 (3-1-1) 7% 3-HHB-O1 (3-4-1) 4% V2-HHB-1(3-4-1) 5% 1V-HBB-2 (3-5-1) 5% V2-BB(3F)B-1 (3-6-1) 3% 3-HHEBH-3 (3-8-1)3% 5-HBB(3F)B-3 (3-11-1) 5% V-HB(2F,3F)-O2 (4-1-1) 5% 5-H2B(2F,3F)-O2(4-2-1) 5% 5-HHB(2F,3F)-O2 (4-4-1) 5% 3-HHB(2F,3F)-1 (4-4-1) 3%3-HH2B(2F,3F)-O2 (4-5-1) 5% 5-HH1OB(2F,3F)-O2 (4-6-1) 5%5-HHB(2F,3CL)-O2 (4-8-1) 3% NI = 104.7° C.; Tc ≦ −20° C.; Δn = 0.109; η= 24.1 mPa · s; Δε = −2.9.

Example 8

7-B(2F,3F)B(2F,3F)-O2 (1-1-1) 3% 2O-B(2F,3F)B(2F,3F)-O6 (1-1-1) 3%4O-B(2F,3F)B(2F,3F)-O6 (1-1-1) 3% 3-DhHB(2F,3F)-O2 (2-4-1) 5%3-HDhB(2F,3F)-O2 (2-5-1) 5% 2-HH-3 (3-1-1) 18% 3-HH-V1 (3-1-1) 5% 5-HB-3(3-2-1) 3% 3-HB-O2 (3-2-1) 3% V2-BB-1 (3-3-1) 3% 3-HHB-3 (3-4-1) 6%V2-HHB-1 (3-4-1) 5% 3-HBB-2 (3-5-1) 3% 3-HHEBH-3 (3-8-1) 5% 3-HBBH-3(3-9-1) 3% 3-HB(3F)BH-3 (3-10-1) 3% 5-HBB(3F)B-3 (3-11-1) 3%V-HB(2F,3F)-O4 (4-1-1) 5% 5-HH1OB(2F,3F)-O2 (4-6-1) 5% 3-HBB(2F,3F)-O2(4-7-1) 5% V-HBB(2F,3F)-O2 (4-7-1) 3% 5-HBB(2F,3CL)-O2 (4-9-1) 3% NI =104.1° C.; Tc ≦ −20° C.; Δn = 0.111; η = 24.0 mPa · s; Δε = −2.8.

Example 9

5-B(2F,3F)B(2F,3F)-O2 (1-1-1) 3% 2O-B(2F,3F)B(2F,3F)-O6 (1-1-1) 3%4O-B(2F,3F)B(2F,3F)-O6 (1-1-1) 3% 3-dhBB(2F,3F)-O2 (2-7-1) 3%4-dhBB(2F,3F)-O2 (2-7-1) 3% 5-dhBB(2F,3F)-O2 (2-7-1) 3% 2-HH-3 (3-1-1)11% 3-HH-V (3-1-1) 6% 3-HH-V1 (3-1-1) 5% V2-BB-1 (3-3-1) 5% 3-HHB-O1(3-4-1) 5% V2-HHB-1 (3-4-1) 5% 2-BB(3F)B-3 (3-6-1) 3% 3-HHEBH-3 (3-8-1)5% 5-HBB(3F)B-3 (3-11-1) 3% 5-HB(2F,3F)-O2 (4-1-1) 3% V-HB(2F,3F)-O2(4-1-1) 5% 5-HHB(2F,3F)-O2 (4-4-1) 5% V-HHB(2F,3F)-O2 (4-4-1) 5%V2-HHB(2F,3F)-O2 (4-4-1) 5% 1V2-HHB(2F,3F)-O2 (4-4-1) 3% 5-HBB(2F,3F)-O2(4-7-1) 4% 5-HHB(2F,3CL)-O2 (4-8-1) 4% NI = 104.6° C.; Tc ≦ −20° C.; Δn= 0.114; η = 24.3 mPa · s; Δε = −3.1.

Example 10

7-B(2F,3F)B(2F,3F)-O2 (1-1-1) 3% V2-B(2F,3F)B(2F,3F)-O2 (1-1-1) 3%2O-B(2F,3F)B(2F,3F)-O6 (1-1-1) 3% 4O-B(2F,3F)B(2F,3F)-O6 (1-1-1) 3%6O-B(2F,3F)B(2F,3F)-O8 (1-1-1) 2% 5-DhHB(2F,3F)-O2 (2-4-1) 3%3-HDhB(2F,3F)-O2 (2-5-1) 3% 3-HH-V (3-1-1) 31% 3-HHB-O1 (3-4-1) 5%3-HHEBH-3 (3-8-1) 5% 3-HHEBH-5 (3-8-1) 5% 5-HBB(3F)B-2 (3-11-1) 3%5-HBB(3F)B-3 (3-11-1) 3% V-HB(2F,3F)-O2 (4-1-1) 3% 5-H2B(2F,3F)-O2(4-2-1) 4% 3-HHB(2F,3F)-O2 (4-4-1) 5% V-HHB(2F,3F)-O2 (4-4-1) 3%5-HH2B(2F,3F)-O2 (4-5-1) 5% 5-HBB(2F,3F)-O2 (4-7-1) 8% NI = 103.8° C.;Tc ≦ −20° C.; Δn = 0.103; η = 24.9 mPa · s; Δε = −3.0.

The compositions of Examples 1 to 10 have a high maximum temperature ofa nematic phase and a small viscosity in comparison with those inComparative Examples 1 to 4. Thus, the liquid crystal composition of theinvention is so much superior in characteristics to the liquid crystalcompositions disclosed in the patent documents No. 1 to No. 4.

Industrial Applicability

The invention provides a liquid crystal composition that satisfies atleast one of characteristics such as a high maximum temperature of anematic phase, a low minimum temperature of a nematic phase, a smallviscosity, a suitable optical anisotropy, a large negative dielectricanisotropy, a large specific resistance, a high stability to ultravioletlight and a high stability to heat, or that is suitably balancedregarding at least two of the characteristics. A liquid crystal displaydevice containing such a composition becomes an AM device that has ashort response time, a large voltage holding ratio, a large contrastratio, a long service life and so forth, and thus it can be used for aliquid crystal projector, a liquid crystal television and so forth.

1. A liquid crystal composition that has negative dielectric anisotropyand includes at least one compound selected from the group of compoundsrepresented by formula (1) as a first component and at least onecompound selected from the group of compounds represented by formula (2)as a second component:

wherein R¹ and R² are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkenyloxyhaving 2 to 11 carbons, or alkenyl having 2 to 12 carbons in whicharbitrary hydrogen is replaced by fluorine; R³ and R⁴ are independentlyalkyl having 1 to 12 carbons, alkoxy having 1 to 12 carbons, alkenylhaving 2 to 12 carbons, or alkenyl having 2 to 12 carbons in whicharbitrary hydrogen is replaced by fluorine; the ring A is independently

and at least one of the rings A is

X¹, X², X³ and X⁴ are independently hydrogen, fluorine or chlorine, andat least three of X¹, X², X³ and X⁴ are fluorine; Z¹ is independently asingle bond, ethylene, methyleneoxy or carbonyloxy; and k is 1, 2 or 3.2. The liquid crystal composition according to claim 1, wherein thefirst component is at least one compound selected from the group ofcompounds represented by formula (1-1) to formula (1-3):

wherein R¹ and R² are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, alkenyloxyhaving 2 to 11 carbons, or alkenyl having 2 to 12 carbons in whicharbitrary hydrogen is replaced by fluorine.
 3. The liquid crystalcomposition according to claim 2, wherein the first component is atleast one compound selected from the group of compounds represented byformula (1-1).
 4. The liquid crystal composition according to claim 2,wherein the first component is a mixture of at least one compoundselected from the group of compounds represented by formula (1-1) and atleast one compound selected from the group of compounds represented byformula (1-2).
 5. The liquid crystal composition according to claim 1,wherein the second component is at least one compound selected from thegroup of compounds represented by formula (2-1) to formula (2-7):

wherein R³ and R⁴ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine.
 6. The liquid crystal composition according to claim 5,wherein the second component is at least one compound selected from thegroup of compounds represented by formula (2-4) to formula (2-7).
 7. Theliquid crystal composition according to claim 1, wherein the ratio ofthe first component is in the range of 5% by weight to 40% by weight andthe ratio of the second component is in the range of 5% by weight to 60%by weight, based on the total weight of the liquid crystal composition.8. The liquid crystal composition according to claim 1, furtherincluding at least one compound selected from the group of compoundsrepresented by formula (3) as a third component:

wherein R⁵ and R⁶ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; the ring B and the ring C are independently 1,4-cyclohexylene,1,4-phenylene, 2-fluoro-1,4-phenylene or 3-fluoro-1,4-phenylene; Z² isindependently a single bond, ethylene, methyleneoxy or carbonyloxy; andm is 1, 2 or
 3. 9. The liquid crystal composition according to claim 8,wherein the third component is at least one compound selected from thegroup of compounds represented by formula (3-1) to formula (3-11):

wherein R⁵ and R⁶ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine.
 10. The liquid crystal composition according to claim 8,wherein the ratio of the third component is in the range of 10% byweight to 80% by weight based on the total weight of the liquid crystalcomposition.
 11. The liquid crystal composition according to claim 1,further including at least one compound selected from the group ofcompounds represented by formula (4) as a fourth component:

wherein R⁷ and R⁸ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; the ring D is independently 1,4-cyclohexylene or1,4-phenylene; Z³ is independently a single bond, ethylene, methyleneoxyor carbonyloxy; X⁵ and X⁶ are independently fluorine or chlorine; and nis 1, 2 or
 3. 12. The liquid crystal composition according to claim 11,wherein the fourth component is at least one compound selected from thegroup of compounds represented by formula (4-1) to formula (4-9):

wherein R⁷ and R⁸ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine.
 13. The liquid crystal composition according to claim 11,wherein the ratio of the fourth component is in the range of 5% byweight to 40% by weight based on the total weight of the liquid crystalcomposition.
 14. The liquid crystal composition according to claim 1,wherein the maximum temperature of a nematic phase is 70° C. or higher,the optical anisotropy (25° C.) at a wavelength of 589 nanometers is0.08 or more, and the dielectric anisotropy (25° C.) at a frequency of 1kHz is −2 or less.
 15. A liquid crystal display device containing theliquid crystal composition according to claim
 1. 16. The liquid crystaldisplay device according to claim 15, wherein an operating mode of theliquid crystal display device is a VA mode, an IPS mode or a PSA mode,and a driving mode of the liquid crystal display device is an activematrix mode.
 17. The liquid crystal composition according to claim 8,further including at least one compound selected from the group ofcompounds represented by formula (4) as a fourth component:

wherein R⁷ and R⁸ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine; the ring D is independently 1,4-cyclohexylene or1,4-phenylene; Z³ is independently a single bond, ethylene, methyleneoxyor carbonyloxy; X⁵ and X⁶ are independently fluorine or chlorine; and nis 1, 2 or
 3. 18. The liquid crystal composition according to claim 17,wherein the fourth component is at least one compound selected from thegroup of compounds represented by formula (4-1) to formula (4-9):

wherein R⁷ and R⁸ are independently alkyl having 1 to 12 carbons, alkoxyhaving 1 to 12 carbons, alkenyl having 2 to 12 carbons, or alkenylhaving 2 to 12 carbons in which arbitrary hydrogen is replaced byfluorine.
 19. The liquid crystal composition according to claim 17,wherein the ratio of the fourth component is in the range of 5% byweight to 40% by weight based on the total weight of the liquid crystalcomposition.